Method and apparatus for continuously plating irregularly shaped objects



May 12, 1953 O, D s ETAL 2,638,423

METHOD AND APPAR S FOR CONTINUO S Y PLATING IRREGULARLY SHAPED OBJEFiled Aug. 25, 1949 3 Sheets-Sheet 1 FIG 1 m INVENTORS N OLIVER F. s

m HANS G.BELI

ATTORNEYS n 5 s v 4, m fin I. N w a M l. 7 6 u Err E V B T 2 6 NR A eIE6 h N 3 A DAVIS ET AL 0. F. METHOD AND APPARATUS FOR CONTINUOUSLYPLATING IRREGULARLY SHAPED OBJECTS May 12, 1953 Flled Aug 25, 1949Patented May 12, 1953 METHOD AND APPARATUS FOR CONTINU- OUSLY PLATINGIRREGULARLY SHAPED OBJECTS Oliver F. Davis, Troy, and Hans G. Belitz,Dayton,

Ohio, assignors to The Commonwealth Engineering Company of Ohio, Dayton,Ohio, a

corporation of Ohio Application August 25, 1949, Serial'No. 112,308Claims. (Cl. 117-+50) This invention relates to the art of thedeposition of metals. More particularly, it relates'to the coating ofsmall metal objects ofirregular shape. Still more particularly itrelates to the plating of objects by the deposition of metal fromreadily decomposed metal bearing compounds and apparatus for carryingout the process.

Depositing of thin films of metals such as iron, nickel, cobalt, and soforth, upon metal bases has been accomplished in the past by enclosingand object to be plated in a chamber, charging the chamber with adecomposable metal-bearing gas and heating the object to thedecomposition temperature for said metal-bearing gas.

In the only process of which applicants have knowledge, whereinan objectis moved in; the plating zone, the material is thin metal sheet. Thisfiat material is brought to the gas decomposition temperature by,resistance heaters placed on the underside of the sheet. The upper sideof the sheet is exposed to the decomposablegases, and a metallic coatingis deposited upon only one side of the metal sheet. This metal sheet isbrought into and outoi-the-plating chamber by passing the sheet'througha'water bath which-acts as a seal forthegas chamber. 1

. The above described operations have many disadvantages, chief of whichwas thediscon tinuity of the processes other than the last described. Iv

In the latter operation'continuous plating was only possible dition,these strips were brought intotheplat ing chamberthrougha liquid sealingbath, which bath had the effect of wetting the surfaceoi the metal andleaving enough liquid onthe surface to interfere with goodmetal'deposition. J

Itv is an objectof this invention to overcome thedisadvantagesandlimitations of the processes'known heretofore.

It is another object of this invention to providc a process which iscontinuous. g

It is a still further object of this invention to' provide a process toplate'objects other than flat surfaces on a continuous basis. a

It is another object'of this invention to provide a process whereinobjects are chemically cleaned and plated and the coating renderedductile by heating in a continuous operation which may be handled with aminimum of labor.

A still further object'of; this invention isto." provide apparatus whichallows continuous movement of objects into the plating zone withoutpassing through a metal wetting seal.

upon one side of fiat strips. in ad-.

Another object of this invention is to provide a new style look forplating chambers which allows ingress of objects without danger ofescapeof toxic gases into the outside atmosphere.

It'is another object of this invention to provide a process which may beoperated under either positive or negative pressure conditions.

Another object is to provide apparatus having a single chamber dividedinto segments by a simple divider mechanism which, in conjunction withcontrol of gas pressure, seals the apparatus against leakage of platinggas.

Other and more specific objects and advantages will be apparent to oneskilled in the artas the following description proceeds; 1

In this new process small objects are mounted in a fixture carried bya-continuous belt. This fixture supports the objects in an extendedposition, so that in their early travel they project downward intosolution baths, then reverse their course and project upwardly, whilepassing through plating and annealing chambers.

In this way it is possible to get compact equipment operable with aminimum of costly manual labor. It also provides meansfor countercur--rent movement of objects and plating gas through a plating chamber.

The atmosphere in the plating chamber may be maintained either atpressures above atmospheric or at pressures below atmospheric maintainedby suction or'vacuum drawn on the chamber.

It is possible in this new process and apparatus to utilize a gaseousatmosphere formed by mixing an inert gas with the vapors of a volatilemetal compound or by atomizing a liquid metal compound into a blast ofhot inert gas or other equivalent method.

Thus, it is possible to use volatile metal compounds which are or can beconverted into vapors either by themselves or by making solutions of themetal compound and highly volatile solvents.

When introducing the metal compounds the vapors are, generally dilutedwith an inert gas, carbon dioxide, helium, nitrogen, hydrogen, the;gaseous product of controlled burning of hydrocarbon gases free ofoxygen, and the like, have been utilized as a carrier medium as well asbeing the inert gas medium utilized in the nonplating operation.

In some instances the use of hydrogen is preferred, as for example, inthe cleaning anneal chamber Where its ability to act as a reducingbonyls, for example, cobalt nitrosyl carbonyl; hy

drides, such as antimony hydride, tin hydride; metal alkyls, such aschromypphlorideaand carbonyl halogens, for example, osmium carbonylbromide, ruthenium carbonyl chloride, and the like.

Each material r from which a unetal may be plated has a temperatureatwhich-decomposition is -complete. However, decomposition --=ma-ytakeplaceslowlw-ata lower temperature orwhile the vaporsarebeing-raised intemperature through some particular-range. For-example-nickel carbonylcompletely decomposes at a temperature in the=range f"375 -'F: to400"=F. Howeven-nickel carbonyl starts to --decompose slowly at about 175and, therefore, decomposi-tion continues during the time of heatingfrom=200* F.=to 380 -F.

A large number of the-metal carbonyls-and-hydrides may be-effectively--and eilicientl-y decomposed at atemperaturein the range of 350 F.-to

450 F. When working -with most metal -carbonyls we prefer to operate---i-n -a temperature range of 37-5 F.--to-425'F.

"Maintenance -01 'the object -at temperatures generally: in thedecomposition range iyreadily accomplished by-=causing= the obiecttobeheated by I infrared-- rays orby induction heating. T-he advantage --ofthis type of a heating w is l its ready control within 1 the temperatureranges utilized in the process. These :tem-pera-tures -generaily rangeirorn 350 F.-to 450F.inthe plating zones and from 800 l to 1200" F.inthe annealing zones.

',-Preparatory: to coating the objeetsi-the obj ects maybecleanedbyiemploying conventional methods.-.used. in: the art, comprisingsimplecoatings through: electrochemical cleaning -by moving the object throughbaths of alkali or acid electrolyte.

iWhen .the -objects {are =me-tal they "may --bepickled.=.withxhydrochloric,-sulfiuric or nitrimacid, or.:.acombinationsof acida and the .obiect then thoroughly rinsed .and avashedpricruto -I further reatment.

The invention will be more filearlyzunderstw fromt e:f l ow n d ser tinninn embodiment of, the apparatus and-,its, mode of ;.ope rzaft ion.

Inih dra n s 1 ,Figure, 1 is aperspectiye view ofthe. equipment withportions cut away to disclose the inte nal appa us a ran emen F re? is adia mma illustration oflthe process "stepscarried out in "the apparatusof Figure l *FigureB is =an-elevational-view partly in section of the.fixture and the-shanhofan object to be plated;

Figurezijs a.-. -view; along the line-44M of' Figure 3;

tFigurefi is a perspectiverview of the :continuous bflltand the:supports for. thezfixtures lEi iuifej Gi h plan Y-ieW Ofimeuppemplatinghpor- 4 tion of the apparatus with the roof cut away overvarious locks and chambers;

Figure 7 is a View along the line II-71 of Figure 6;

:Figure' 8;is a; perspective view cfthe drive and continuous belt patharrangement whereby objects are carried through various baths;

Figures 9 and 10 are enlarged views of the re- ;silient partition, gaslocks showing the progress :of an object throughsaid lock and Figure1l.-.;is;an; elevational view of the foot control for the apparatusactuated by the operator 1oacling and unloading fixtures.

Referring to the drawings in detail, first in connection with-Figures land 5, there is shown objects Hl,"in' this case illustrated as heads ofa ulfrclub.

Objects, iii are mounted on fixtures H which arecarried by a continuousbelt 52 such as a chain belt. Belt i2 is supported and actuated bysprockets is and l mounted on framework i5.

-Framework iii ii-iterrnediate the-endsproCkEt forms abase for supportof the bottomseries of units indicated at l-dinore details of which'willbe'givenuponreference toFigureZ, and an upper seriesof-cha-mbersorconduits indicated at 5?, more details of which will be givenwithrelation to Figuresfi and 7 Sprocket 43 is in an enclosed r-chamberit which is; providcdwith inlet'and outlet ducts i9 and "29 forintroduction and removal of hot air. Sprocket i3 is the primary-driveunit for the belt I? andis driven through drive shaft-2 l and-gears 22from a-sou-rce of power'fifi such' as an electric motor.

""Drive shaft 2-! also-carries a gearil-which meshes with a-gear25 enthe-shaft 26. As indicated in Figure -8 shaft- 26 carries gears 2'!which drive gears iid which are mounted-on shaft 29 for 'directing "anddriving the chain belt 12 throu h the series of tanksof unit it.

As indicated in Figure 2- unit I5 is a-series of tanks 39 to 36,inclusive, --enclosed' in a housing 31. *Housing e'l carriesthebearings-BS audits for shafts 26 and for shaftsl 8, respectively.

-=Inthe-upperportion of housing "37 is mounted the chamber unitindicatedat W. This unit consists of a'number ofcompartments, herein illustrated'with-fthree compartments M, 42 and 43.

As'in-dicatedi-n Figure-"2,- compartment Jll is adapted for heating theobjects in an inert atmosphere. Compartment ll is closed-at the endswith locks 44 and 2 5' and the lockpartition framework Mu andjfiSa,:respectively, and has a glassitop side ldthrough which infrared heatingraysxmay' be 'directed'jfrom lamps ii. Compartment isprovided-with'gaseous inlet and outlet uct 48 a d v.LCIomnartment 42 is,similar to. compartments 4| and '43, being separatedtherefrom,bylocks45,.and .-50. For safety in preventingleakage of toxic carbon monoxide,compartment 42 isof double ;-cons.t-r1 1ction as illustrated, in, Figure'7.

-;.'I!he compartment ,as illustrated, consists, ofta r tan ular CrOSs,1sect onal;.ccznlui v 5| mounted inwunit l1 framework. Within the;-conduit g5! is-asmaller conduit-52 of. rectangular cross section. Each:of .these conduits is provided .with :a glass topwhen infrared"heatingis utilized.

-0onduit 52 -=is --the -:p1ating chamber through which belt I2conveysobiects H]. Conduit 52 is provided with inlet and outlet gasconduits -53 andi5'4.

The spaee:;hetweemconduits-j I and-152 is -prgs1 vided with in resslationofinertgas.

The housing. 3:! iiseprovided withtaig iassrtnptfiia overizthecompartment :42: Heat :raysane direeted j into compartment 42 iirominfrared ilamps 55st,-

suspended tromtthe. lightzfixturefi Compartments is sham-orbitstturthersend: bysloek and itszpartition framework-11m; 1

compartment :is 'i-prouideu with-gas: i iletuandzaowte let iconduitsifil:and fl.

The .1oohs-.permitt'mg rpasszge of asolid obieots. carried thy thebeltzare',turtheriifllustratethin rm ures 9 sand'illfl with meierenoei110 hook/50. Eiscgnsists of spaced: Nita-11s Ems-and 2111' havingresilient: arms :12,- 113,14 andazISasextenritng ithere between. 7

Each arm is made up of two half sections,-:'or-

example, ziza-zandv :Ub; Eaoh .sarmlzis ilateraliyspacedrtoiprovideraireohamhers; only'tw .iofiwhioh; are :inacommunioation. an object: massing;

through ,one :arm.

.As .i'llustratedin z'Figure .9 when, .cobiectirlzfl starts throughaloe]: :itucontaets term: 512;. center Z01 separation point; :By thetime ithe:

object .is roontactmgarms (E'ieurealthftherohieotris zeiear of armlzzpermitting theta-rm close sand thus prevents iineresssof 1am.thererare :two orxmore 'armsrhlosingrthesentmnoeor-sexit :to gas'transierzdurihg-athe massa e 510i an.

SEhe fobiert. passing: through a dock: :mustzbe securely fixed to.itsuppert detailed} rim-1s.- tration ofga fixture-m1.fiecurihgianrohjectzis shawlv inEieuresB nd =4,

the lengthvoi the platingschamber,forthedepflsiw tion of a. fixedthioknesstof: coating ton ztheiobjeot having a ce tai surfaceareat vOther variables relatedto deposition. of metal are present in theproc.es,s ,ii 2r example, the.grinoen'tration of carbonyl vapors, fed" .0thfl pla a chamber. Itwill be understood; therefore, that thefollowing'iiescription unereiy is -fi1ust: 1"a't ive ofthe-oonditions which are-operative fora given bel t-speed-and tor-objects of a'g-iven sizeand=for plating aspecifio depth tofcoati-ne', and met hywayuofw'timitation.

:fio1f.;o1ub heads arehnounted.tonefixturesel I got belt 12 as shown inFigure 2 at the loadingszone. he be1t- 2 marmoveat ithematerozfsz ie timm u eh r ootofihlatiheztchamber.

The belt carries the headthnoueh ardeereasma chamber '35 where it iswashed with greaseisob vents such as light qnaphtlia.v The ,belt thenmoves the object through ,a1caustio bathlin'tank 35, which may consistof '4 normalwsoldiuih .hy-

droxide solution. The belt then moves the v .objectthroug'h' hotlanjdcold Water rinses in'pseries.

Following rinsing'the golf club heads are dipped into 'a pickling bathin taiikfiz asjor when en aged. wine;

Menuhin-mu erdriedzinrohmnheratflwheresa elean hat-rairiaassttureaofsapproximatew lmwfh'risseineulated:

The golf h ad t nassestthrongahttookmlontooouohantmentzflmaintainedtwithzaminentratmoshheresofrearhomdioxideteas:undei'zamressureaofibout mounds ii nohzgagei hassmg-tthmueh :reompartnmnt: 14:1: thegotftolubeheom sizheateki ttosanotoximateiyufleot E: H'he heatedr'zheadaathenmasses.rthroilehjflouk 45 time thesptflingaeuwortmentifl;z'limsvoomeuartmenti. edatmoisturetuttitaizhonadioxhie:seas-.anuzmetaiseorbonui;:zsuehre miokel-icarhonyhsat argassrateon 'thesnaneeofczfi-tto 1t ouhicfifeetmen mfitmte-tmithazthe; iter tetra-mp1s,- iokeheauhottyh eontenttoi aipmoztimatehr touno'ssof harhorw huorouhieifootz-zof-seathon oxide.

"itihesheadsxzmaiy tplartedeto savsdenhhrofzuwz ihohnintaaflssecon'cltplhting-sintewflili 'ithethlzazted; headtmoues' 'hrougvh.loekzifioi'intoithereooling som partmentifiwhere'xheiheaeisecoolunzaooldxinent gaswatmospheneb xusually rcarhon fliQXide= igaL maintainedunder 30 mounds :nefr. square inch:

eas -r iwhema long plating iohamher isrnsedia'nd-rthe; belt atheretorv fspeededgfiihe :Zbfll'ib' :r-may' :be trims/en; by aunotoreleotri-oailwoonneeted for'rnomentesrst interruption of drive to a footpedalflflmrsarifltfitratediimhigure '1m',-'Whieh.;aisruhderetheseuntroizof the-toperator attherloadingtzonezlt-nvinazbewunoierstood rthatzimrhile :the :method' and apparatus:disolosed rdesoribosl; hemm; illustrate :a pretetredfior-moi'iiureirtion, amortifloations lean 'bermaue wi thatttx dehartm rfmmcthespirit of the invention, and tmottifieationfi; that fall within the.scope ofthe a ppenderi relafims are i-n-tendedwto" moulded therein.

=1. A m-ether otf platingiob ieotsi'lo tithe zelehosiftion of "metalfirom heat-decomposable :metal compoimds which:oomprisos -therfibeps.;of:o-onuey,- ing *sa'zid objeets to he :plated while ;masi=ntainectin-spaoeei reiations'hip with respect toseaehnother through aplatingohambei', oireulating Egg 333G118 metat compound through said chamber,yheatine saiwobjeots by contaoti-ng the same twith a :hot gaseous-me'diumwhile the: same are conveyed thereaklong and :prior to enteringchamber,

thereafter movingsaid objects -i-ntoisaid -platm chamber and subjectingthe same to" a tempera:- ture sufiioienttowcause decomposition.iofpsafid gaseousmeta1-compound in said chamber and deposition o f-meta1 on saiti-ohieets white :the

, sameareeonveyed'there along throughzsaidfiplats ing --oham ber-,and-subjecting said obj acts "to a inert gaseous =ooo1ing mediumraifterapassageof the same *from said ohamber and before said obj 861393339conveyedintothe open atmosphere.

'92. 'Kmethod ofimating (objeets by' the-: rieposittionof metal fromheat-decomposable -meta1 compounds which comprises-the steps -of conveying 5895M objects sto be platedthrough a; plating chamber mutating-s agaseous metal compound throughasaid charmbeiy heating-said ;;Obj0b$bycontacting thesame-With a hot gaseousmedium prior to conveyingthee'same intosaid oham10er- .to "a. temperature "S'Ii ffiCieHt to=eause -decompesistion 'ofsaid gaseous metal compound -said chamberanddeposttion-uf meta hon said obieots while the same-rare :oonteyed:atherealongithrongh said tpl'ating zchamber, conveyin -15am heatedobjects into said plating chamher hohauseheeomhositionsoafasaidsaeeousunetalztoomoumi and .demsitmntoftmetahonraaidmhiects;who

ing said objects to an inert gaseous cooling me-' dium after passage ofthe same from said chamber and before said objects are conveyed into theopen atmosphere, said heating being carried out in an inert atmosphere.

3. A method of plating objects by the: deposition of metal fromheat-decomposable metal compounds which comprises the steps of conveyingsaid objects to be plated while maintained in spaced relationship withrespect to each other;

to cause the decomposition of said gaseous metal compound in saidplating chamber and deposition of metal on said objects while the sameare con-' veyed through said chamber, said gaseous metalcompound beingselected from the group consisting of the gaseous metal carbonyls ofchromium, nickel, iron, molybdenum, cobalt and mixtures thereof, andsubjecting said objects to an inert gaseous cooling medium aftermovement of the same through said plating chamber and before conveyingsaid plated objects into the open atmosphere.

4. A method of plating objects by the deposition of metal fromheat-decomposable metal compounds which comprises the steps of conveyingsaid objects to be plated while maintained in spaced relationship withrespect to each other through a plating chamber, circulating gaseousmaterial through said plating chamber at least a portion of whichcomprises a heat-decomposable metal compound, heating said objects bycontacting the same with a hot inert gaseous medium prior to enteringsaid plating chamber, said objects being heated to a temperaturesufficient to cause decomposition of said gaseous metal compound in saidplating chamber and deposition o-f metal on said objects while the sameare conveyed through said chamber, said gaseous metal compoundconsisting of nickel carbonyl, and subjecting said objects to an inertgaseous cooling medium after movement or the same through said platingchamber and before conveying said plated objects into the openatmosphere.

5. A method of plating objects by the deposition of metal fromheat-decomposable metal compounds which comprises the steps of conveyingsaid objects to be plated while maintained in spaced relationship withrespect to each other through a plating chamber, circulating gaseousmaterial through said plating chamber at least a portion of whichcomprises a heat-decomposable metal compound, heating said objects bycontacting the same with a hot inert gaseous medium prior to enteringsaid plating chamber, said objects being heated to a temperaturesufficient tocause decomposition of said gaseous metal compound in saidplating chamber and deposition of metal on said objects while the sameare conveyed through said chamber, said gaseous metal compoundconsisting of chromium carbonyl, and subjecting said objects to an inertgaseous cooling medium after movement of the same through said platingchamber and before conveying said plated objects into the openatmosphere.

6. In a method of plating objects by the depocompounds comprisingconveying said objects to be plated while heated through a chamber inwhich is circulated a heat-decomposable metal compound, the improvementwhich consists in preheating said objects to a temperature surficient todecompose said heat-decomposable metal compound in the plating chamberby subjecting said objects while the same are conveyed along toward saidplating'chamber to an inert hot gaseous medium, thereafter conveyingsaid preheated objects into said plating chamber to cause decompositionof said heat-decomposable metal compound and deposition of metal on saidobjects, and cooling the plated objects after passage of the same fromsaid chamber by subjecting said objects to an inert gaseous coolingmedium.

7. In apparatus for continuously plating objects of irregular shape, thecombination comprising an endless belt; fixtures carried by said beltfor holding objects thereon in spaced relation; guides for said beltdirecting its travel through a plating chamber; mechanical lockslimiting gaseous movement at the inlet and outlet of said chamber; saidlocks comprising spaced flexible walls having a separable portiontherein for the passage therethrough of objects to be plated; heatingmeans for said objects; and inlet and outlet means for introducing andremoving gaseous material from said chamber.

8. In apparatus for continuously plating objects of irregular shape, thecombination comprising an endless belt; fixtures carried by said beltfor holding objects thereon in spaced relation; guides for said beltdirecting its travel through conduits joined in series; mechanical lockslimiting ingress and egress of gaseous material from each conduit; saidlocks comprising spaced flexible walls having a separable portiontherein for the passage therethrough of objects to be placed; heatingmeans associated with one of said conduits; and inlet and outlet meansfor introducing and removing gaseous material from each conduit.

9. In apparatus for continuously plating objects the combinationcomprising an endless belt; fixtures carried by said belt for holdingobjects thereon in spaced relation; a series of tanks; guides for saidbelt directing the belt in a path carrying the objects into and out ofeach tank; a drying chamber; means in said drying chamber for reversingthe direction of said belt; conduits adapted to have the belt traveltherethrough in series; mechanical locks limiting ingress and egress ofgaseous material from each conduit; said locks comprising spacedflexible walls having a separable portion therein for the passagetherethrough of objects to be plated; heating means associated with oneof said conduits; and inlet and outlet means for introducing andremoving gaseous material from each conduit.

10. In apparatus for continuously plating objects the combinationcomprising an endless belt; fixtures carried by said belt for holdingobjects thereon in spaced relation; guides for said belt directing itstravel through an elongated chamber; mechanical locks at the inlet andoutlet of said chamber and at positions dividing said chamber intosegments, said locks consisting of a series of spaced flexible wallsdivided along the central vertical axis; heating means associsltion ofmetal from heat-decomposable metal F? with Segments adjacent the inlet;d

conduit means for introducing and removing Number Name Date gaseousmaterial from each chamber segment. 1,981,149 Parker et a1. Nov. 20,1934 OLIVER F. DAVIS. 2,159,297 Shover 1- May 23, 1939 HANS G. BELITZ.2,332,309 Drummond Oct. 19, 1943 5 2,344,138 Drummond Mar. 14, 1944References Cited in the file of this patent 2,3 7,174 ki Jan 9, 1945UNITED STATES PATENTS 2,384,500 StOll Sept. 11, 1945 Number Name Dat2,405,662 McManus et a1. Aug. 13, 1946 9 2,442,485 Cook June 1, 19481,804,484 Wetmore May 12, 1931 m

1. A METHOD OF PLATING OBJECTS BY THE DEPOSITION OF METAL FROMHEAT-DECOMPOSABLE METAL COMPOUNDS WHICH COMPRISES THE STEPS OF CONVEYINGSAID OBJECTS TO BE PLATED WHILE MAINTAINED IN SPACED RELATIONSHIP WITHRESPECT TO EACH OTHER THROUGH A PLATING CHAMBER, CIRCULATING A GASEOUSMETAL COMPOUND THROUGH SAID CHAMBER, HEATING SAID OBJECTS BY CONTACTINGTHE SAME WITH A HOT GASEOUS MEDIUM WHILE THE SAME ARE CONVEYEDTHEREALONG AND PRIOR TO ENTERING SAID CHAMBER, THEREAFTER MOVING SAIDOBJECTS INTO SAID PLATING CHAMBER AND SUBJECTING THE SAME TO ATEMPERATURE SUFFICIENT TO CAUSE DECOMPOSITION OF SAID